Artificial disc

ABSTRACT

A medical device includes a base ring configured to be implanted within a body of a patient. The base ring provides a contact surface to a vertebra. Multiple layers of multiple leveling plates are configured to equalize forces applied to the contact surface of the base ring, where at least one of the layers of the leveling plates engages an inner surface of the base ring. A layer of multiple pads is included with a top surface of the pads configured to maintain a parallel plane and a bottom surface of each of the multiple pads is configured to engage a top surface of one of the layers of the leveling plates. A cover is configured to enclose the multiple layers of the leveling plates, the layer of the multiple pads and the base ring. The cover provides a contact surface to a vertebra.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation application of U.S. patentapplication Ser. No. 15/260,466 filed on Sep. 9, 2016 (published as U.S.Patent Publication No. 2016-0374827), which is a continuation of U.S.patent application Ser. No. 14/070,171 filed on Nov. 1, 2013 (now issuedas U.S. Pat. No. 9,463,095), which is a continuation application of U.S.patent application Ser. No. 13/421,121 filed on Mar. 15, 2012 (nowissued as U.S. Pat. No. 8,597,355), both of which are incorporated intheir entirety herein by reference.

TECHNICAL FIELD

This description relates to medical devices and more particularly to anartificial (or prosthetic) disc configured to be coupled to a portion ofthe spine.

BACKGROUND

A variety of medical devices and medical device systems may be implantedwithin a body of a patient to provide support to a portion or portionsof the patient's body. For example, some medical devices may beimplanted and coupled to backbones or portions of a spine of a patientand may be configured to provide support to the spinal bone structure ofthe patient.

When a vertebra of a patient is traumatized (e.g., damaged or diseased),a need for surgery may arise to replace and/or repair the traumatizedvertebra.

SUMMARY

According to one general aspect, a medical device includes a base ringconfigured to be implanted within a body of a patient. The base ringprovides a contact surface to a vertebra. The medical device includesmultiple lower leveling plates having a non-flat bottom surface. Thenon-flat bottom surface of each of the multiple lower leveling platesengages an inner surface of the base ring and each of the multiple lowerleveling plates is held in place within the base ring by a memberextending from the base ring through a bore in the lower leveling plate.Multiple upper leveling plates have a bottom surface. The bottom surfaceof each of the multiple upper leveling plates engage a top surface ofthe multiple lower leveling plates and each of the multiple upperleveling plates is held in place within the base ring by a memberextending through the upper leveling plate and engaging bores in thebase ring. Multiple pads have a top surface and a bottom surface. Thetop surfaces of the multiple pads are arranged and configured tomaintain a parallel plane and the bottom surface of each of the multiplepads engage the top surface of the upper leveling plates. A cover isconfigured to enclose the multiple lower leveling plates, the multipleupper leveling plates, the multiple pads and the base ring. The coverprovides a contact surface to a vertebra. A compressible member isarranged through a center of the multiple lower leveling plates, themultiple upper leveling plates and the multiple pads and thecompressible member has a top surface that engages the cover.

Implementations may include one or more of the following features. Forexample, the base ring may define a disc shape and the base ring maydefine a space between an inner wall and an outer wall. The spacebetween the inner wall and the outer wall is configured to receive themultiple lower leveling plates and the multiple upper leveling plates.The inner wall of the base ring defines an area to receive thecompressible member. A top of the outer wall of the base ring definesmultiple areas to receive the multiple pads.

The multiple lower leveling plates and the multiple upper levelingplates are configured to equalize and distribute forces applied to thecontact surface of the base ring with the vertebrae and the contactsurface of the cover with the vertebrae. The multiple pads maintain theparallel plane using the multiple lower leveling plates and the multipleupper leveling plates. The non-flat bottom surface of the lower levelingplates is defined by a first flat area contouring to a sloped round areacontouring to a second flat area. Each of the multiple lower levelingplates may be symmetrical about its center. The bore in each of themultiple lower leveling plates may extend through a center of the lowerleveling plate from the top surface to the bottom surface. The topsurface of each of the multiple pads may be flat and the bottom surfaceof each of the multiple pads may define a platform having a raisedspherical member on a top surface of the platform. The cover may definea circumferential wall having a lip at a top of the circumferentialwall. The compressible member is contained within a diameter defined byan inner wall of the base ring. The compressible member may be abiocompatible, flexible material.

In another general aspect, a medical device includes a base ringconfigured to be implanted within a body of a patient. The base ringprovides a contact surface to a vertebra. Multiple layers of multipleleveling plates are configured to equalize forces applied to the contactsurface of the base ring, where at least one of the layers of theleveling plates engages an inner surface of the base ring. A layer ofmultiple pads is included with a top surface of the pads configured tomaintain a parallel plane and a bottom surface of each of the multiplepads is configured to engage a top surface of one of the layers of theleveling plates. A cover is configured to enclose the multiple layers ofthe leveling plates, the layer of the multiple pads and the base ring.The cover provides a contact surface to a vertebra.

Implementations may include one or more of the following features. Forexample, the medical device may include a compressible member arrangedthrough a center of the multiple layers of the multiple leveling platesand the multiple pads. The compressible member may be contained within adiameter defined by an inner wall of the base ring and the compressiblemember may have a top surface that engages the cover.

The multiple layers of multiple leveling plates may include a layer ofmultiple lower leveling plates having a non-flat bottom surface that isarranged circumferentially inside the base ring. The non-flat bottomsurface of each of the multiple lower leveling plates may engage theinner surface of the base ring. The multiple layers may include a layerof multiple upper leveling plates having a bottom surface that isarranged circumferentially inside the base ring. The bottom surface ofeach of the multiple upper leveling plates engages a top surface of themultiple lower leveling plates. The multiple pads may maintain theparallel plane using the multiple lower leveling plates and the multipleupper leveling plates. The top surface of each of the multiple pads maybe flat and the bottom surface of each of the multiple pads may define aplatform having a raised spherical member on a top surface of theplatform.

In another general aspect, a method includes inserting a prosthetic discinto a portion of an anatomical structure within a body of a patient.The prosthetic disc includes a base ring, multiple layers of multipleleveling plates configured to equalize forces applied to a contactsurface of the base ring and a layer of multiple pads with each of thepads having a top surface and a bottom surface. The top surface of thepads is configured to maintain a parallel plane and the bottom surfaceof each of the multiple pads engages a top surface of one of the layersof the leveling plates. A cover is configured to enclose the multiplelayers of the leveling plates, the layer of the multiple pads and thebase ring. The method includes contacting an outer surface of the basering to a vertebrae and contacting an outer surface of the cover to avertebrae.

Implementations may include one or more of the following features. Forexample, the prosthetic disc may include a compressible member arrangedthrough a center of the multiple layers of the multiple leveling platesand the multiple pads. The compressible member may be contained within adiameter defined by an inner wall of the base ring and the compressiblemember may have a top surface engaging the cover.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features will beapparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of a medical device according to an exemplaryimplementation.

FIG. 2 is a perspective view of a base ring of the medical device ofFIG. 1.

FIG. 3 is a perspective view of a lower leveling plate illustrating abottom surface of the lower leveling plate of the medical device of FIG.1.

FIG. 4 is a perspective view of a lower leveling plate illustrating atop surface of the lower leveling plate of the medical device of FIG. 1.

FIG. 5 is a perspective view of an upper leveling plate illustrating atop surface of the upper leveling plate of the medical device of FIG. 1.

FIG. 6 is a perspective view of an upper leveling plate illustrating abottom surface of the upper leveling plate of the medical device of FIG.1.

FIG. 7 is a perspective view of a pad illustrating a top surface of thepad of the medical device of FIG. 1.

FIG. 8 is a perspective view of a pad illustrating a bottom surface ofthe pad of the medical device of FIG. 1.

FIG. 9 is a perspective view of a cover illustrating a bottom surface ofthe cover of the medical device of FIG. 1.

FIG. 10 is a perspective view of a cover illustrating a top surface ofthe cover of the medical device of FIG. 1.

FIG. 11 is a top view shown in cross-section of the medical device ofFIG. 1.

FIG. 12 is a cross-section view along the line A-A of the medical deviceof view of FIG. 11.

FIG. 13 is a cross-section view along the line B-B of the medical deviceof view of FIG. 11.

FIG. 14 is a flow chart illustrating an exemplary method including themedical device of FIG. 1.

DETAILED DESCRIPTION

The devices and methods described herein are generally directed tomedical devices that can be used to support, stabilize and/or replaceanatomical structures within a body of a patient. In someimplementations, the devices and methods described herein are configuredto provide support to a spine or back of a patient, including providingsupport between two vertebrae in the spine or back of the patient. Inother implementations, other portions of the body of the patient can besupported by the devices described herein.

The medical devices described herein (also referred to as “apparatus” or“device”) may be used as a prosthetic or artificial disc within a bodyof a patient. The terms “prosthetic” and “artificial” may be usedinterchangeably throughout this document to mean the same thing. Themedical devices described herein may be implanted within a body of apatient to assist in maintaining normal physiologic motion in the spineof the patient.

FIG. 1 illustrates an exploded view of a medical device 100, accordingto an exemplary implementation. The medical device 100 includes a basering 102, a layer of multiple lower leveling plates 104 a-104 f and alayer of multiple upper leveling plates 106 a-106 f. The base ring 102may provide a contact surface 108 to a vertebra in a spine of a patient.For example, the base ring 102 may provide a contact surface 108 to mateto the superior endplate of the inferior vertebra within a patient. Themultiple lower leveling plates 104 a-104 f and the multiple upperleveling plates 106 a-106 f may work together to equally distribute theforces applied to the medical device 100. In this manner, the forces maybe equalized and distributed all over an entire surface using the lowerleveling plates 104 a-104 f and the upper leveling plates 106 a-106 f.

The lower leveling plates 104 a-104 f include a non-flat or non-planarbottom surface 110 that engages an inner surface of the base ring 102.Each of the lower leveling plates 104 a-104 f may be held in placewithin the base ring 102 by a corresponding support member 112 a-112 fIn one exemplary implementation, the support members (or members) 112a-112 f may be dowels. The members 112 a-112 f may be received intoopenings or bores on the inner surface of the base ring 102 and extendvertically from the base ring 102 through a bore in each of the lowerleveling plates 104 a-104 f. The non-flat bottom surface 110 on each ofthe lower leveling plates 104 a-104 f may cause the lower levelingplates 104 a-104 f to rock when a force is applied to the top surface114 of the lower leveling plates 104 a-104 f by a bottom surface 116 ofthe upper leveling plates 106 a-106 f.

The upper leveling plates 106 a-106 f may be layered to contact the topsurfaces 114 of the lower leveling plates 104 a-104 f Each of the upperleveling plates 106 a-106 f may be held in place within the base ring102 by a corresponding support member 118 a-118 f that extendshorizontally through a bore in the upper leveling plates 106 a-106 f andengages bores in the base ring 102. In one exemplary implementation, thecorresponding support members 118 a-118 f may be dowels. The dowelsallow movement of the upper leveling plates 106 a-106 f, includingmovement that pivots the upper leveling plates 106 a-106 f about thedowel.

In this exemplary implementation, the medical device 100 includes six(6) lower leveling plates 104 a-104 f and six (6) upper leveling plates106 a-106 f. In one exemplary implementation, the lower leveling plates104 a-104 f are offset from the upper leveling plates 106 a-106 f, basedon the spacing and location of the bores in the base ring 102 (asillustrated in FIG. 2 and described in more detail below). In otherexemplary implementations, the bores in the base ring 102 may be locatedin other positions such that the each of the upper leveling plates 106a-106 f lines up directly on top of one of the lower leveling plates 104a-104 f.

In other exemplary implementations, the number of lower leveling plates104 a-104 f and the number of upper leveling plates 106 a-106 f may varydepending on a size of the base ring 102 and/or on a size of theleveling plates themselves. While the size of each of the lower levelingplates 104 a-104 f is illustrated in this example is uniform or thesame, other exemplary implementations may include different lowerleveling plates 104 a-104 f with non-uniform sizes or sizes that aredifferent from each other. Similarly, while the size of each of theupper leveling plates 106 a-106 f is illustrated in this example asuniform or the same, other exemplary implementations may include upperleveling plates 106 a-106 f with non-uniform sizes or sizes that aredifferent from each other.

In other exemplary implementations, the number of lower leveling plates104 a-104 f and upper leveling plates 106 a-106 f may not be aone-to-one correspondence. For example, in one exemplary implementation,there may be more lower leveling plates 104 a-104 f than upper levelingplates 106 a-106 f. Alternatively, in another exemplary implementation,there may be more upper leveling plates 106 a-106 f than lower levelingplates 104 a-104 f. The variation in the number of lower leveling plates104 a-104 f and upper leveling plates 106 a-106 f may be due, at leastin part, on the size of the leveling plates and/or the size of the basering 102.

The medical device 100 includes a layer of multiple pads 120 a-120 f.The pads 120 a-120 f may be arranged circumferentially around the basering 102. The base ring 102 may define multiple areas 124 a-124 f toreceive the multiple pads 120 a-120 f. Each of the pads 120 a-120 f mayinclude a generally flat top surface 122 and a bottom surface thatincludes a platform area 124 having a raised spherical member 126. Thetop surface 122 of the pads 120 a-120 f may be configured to maintain aparallel plane. The bottom surface having the platform area 124 and theraised spherical member 126 may engage a top surface 128 of each of theupper leveling plates 106 a-106 f.

The top surfaces 122 of all of the pads 120 a-120 f may maintain aparallel plane across the top surfaces based on the equalizing motion ofthe upper leveling plates 106 a-106 f and the lower leveling plates 104a-104 f. While this exemplary implementation illustrates six (6) pads120 a-120 f, other exemplary implementations may use a different numberof pads based on, for example, a size of the pad and/or a size of themedical device 100, including a size of the base ring 102.

The medical device 100 includes a cover 130 that is configured toenclose the lower leveling plates 104 a-104 f, the upper leveling plates106 a-106 f, the pads 120 a-120 f and the base ring 120. The cover 130and the base ring 102 may be configured to hold the assembly together.The cover 130 includes a contact surface 132 configured to contact avertebra. The contact surface 108 of the base ring 102 and the contactsurface 132 of the cover 130 may include a plasma layer, for example inthe form of a spray, on the surface.

The medical device 100 includes a compressible member 134 that is acylindrical-shaped member that is arranged through a center of the lowerleveling plates 104 a-104 f, the upper leveling plates 106 a-106 f andthe pads 120 a-120 f. The compressible member 134 also may be referredto as a cushion. The compressible member 134 may be a shock dampeningcomponent that is made of or includes materials that are flexible andsoft and that provide a shock dampening effect when forces are appliedto the medical device 100.

For example, the compressible member 134 may be a softpolycarbonate-urethane (PCU), rubber, silicone or any other flexiblesoft material that is biocompatible. The base ring 102 may define anarea to receive the compressible member 134 and the compressible member134 may be constrained within the area defined by the base ring 102.

In one exemplary implementation, the compressible member 134 may beslightly longer than the rest of the assembly. As force is exertedbetween the vertebras of the spine causing compression between the basering 102 and the cover 130, the soft compressible member 134 would tryto expand radially. Since the compressible member 134 is containedwithin a fixed radial area defined by the base ring 102, thecompressible member 134 would become more rigid and thus absorb shockforces well.

Referring also to FIG. 2, a perspective view of the base ring 102 ofFIG. 1 is illustrated. The base ring 102 may define a spherical or discshape. The base ring 102 may define an inner wall 240 and an outer wall242. The inner wall may define an opening through which the compressiblemember 134 passes through. A diameter of the opening may constrain thecompressible member 134.

The inner wall 240 and the outer wall 242 may define an area, includingan inner surface 244, that is configured to receive the lower levelingplates 104 a-104 f and the upper leveling plates 106 a-106 f on top ofthe lower leveling plates 104 a-104 f. The inner surface 244 may engagethe non-flat bottom surface 110 of the lower leveling plates 104 a-104f. The inner surface 244 may include multiple bores 246 that areconfigured to receive the members 112 a-112 f that hold the lowerleveling plates 104 a-104 f in position within the base ring 102.

The inner wall 240 may include multiple bores 248 and the outer wall 242may include multiple corresponding bores 250 through which the members118 a-118 f may extend through to hold the upper leveling plates 106a-106 f in position within the base ring 102.

The top of the outer wall 242 may include multiple areas 124 a-124 f orcut outs of the top wall 242 that are configured to receive the pads 120a-120 f. The areas 124 a-124 f may be sized to receive the pads 120a-120 f such that the sides of the pads 120 a-120 f abut to form acontinuous top surface across all of the pads 120 a-120 f.

Referring also to FIGS. 3 and 4, a perspective view illustrates a bottomsurface 110 of a lower leveling plate 104 a (FIG. 3) and a perspectiveview illustrates a top surface 114 of a lower leveling plate 104 a (FIG.4). The lower leveling plate includes a bore 360 there through. The bore360 may extend through the center of the lower leveling plate 104 a fromthe top surface 114 to the bottom surface 110. The bore 360 is sized toreceive the member 112 a to hold the lower leveling plate 104 a inposition within the base ring 102. The lower leveling plate 104 a issymmetrical about its center, where the bore 360 may define the centerof the plate.

As described above the bottom surface 110 of the lower leveling plate104 a is a non-flat or non-planar surface. The bottom surface 110 mayengage the inner surface 244 of the base ring 102 and rock on the innersurface 244 based on the forces applied to the top surface 114 of thelower leveling plate 104 a. The bottom surface 110 may include a firstgenerally flat area 362 that contours to a sloped area 364 and thencontours to a second flat area 366. The sloped area 364 may form a humpon the otherwise generally flat bottom surface 110. The hump allows thelower leveling plate 104 a to rock when forced by one or more of theupper leveling plates 106 a-106 f.

The top surface 114 of the lower leveling plate 104 a is generally flatacross the top. The top surface 114 may be round at the edges and thegenerally flat area may round slightly downward. The top surface 114 mayengage a bottom surface 116 of one or more of the upper leveling plates106 a-106 f.

Referring also to FIGS. 5 and 6, a perspective view illustrates a topsurface 128 of an upper leveling plate 106 a (FIG. 5) and a perspectiveview illustrates a bottom surface 116 of an upper leveling plate 106 a(FIG. 6). The upper leveling plate 106 a includes a horizontal bore 560through its center. The bore 560 is configured to receive a member 118 athat holds the upper leveling plate 106 a in position within the basering 102. When the upper leveling plate 106 a is positioned in the basering 102, the bore 560 is lined up with the corresponding bores 248 and250 on the base ring 102 and the member 118 a is received through thebores 248, 250 and 560 to hold the upper leveling plate 106 a inposition. The upper leveling plate 106 a may pivot about its center onthe member 118 a as forces are applied from one or more pads 120 a-120 fand, in turn, may apply forces to one or more lower leveling plates 104a-104 f.

The bottom surface 116 is configured to engage a top surface 114 of oneor more lower leveling plates 104 a-104 f. The bottom surface 116 isgenerally flat or planar with rounded edges. The top surface 128 isgenerally flat and is configured to engage a bottom surface of one ormore of the pads 120 a-120 f. As can be seen from FIGS. 3-6, the lowerleveling plate 104 a and the upper leveling plate 106 a, are shaped andcontoured to fit circumferentially around the base ring 102.

Referring also to FIGS. 7 and 8, a perspective view illustrates a topsurface 122 of a pad 120 a (FIG. 7) and a perspective view illustrates abottom surface of the pad 120 a (FIG. 8). The pad 120 a is shaped andcontoured to fit circumferentially around the base ring 102. Asdiscussed above, the pad 120 a is configured to engage the base ring inan area 124 a defined by a cut-out of the outer wall 242.

The top surface 122 of the pad 120 a is generally flat or planar. Thepad 120 a is contoured and shaped to abut the other pads such that thetop surface 122 of all of the pads may form a flat or planar surfacethat maintains a parallel plane using the action of the lower levelingplates 104 a-104 f and the upper leveling plates 106 a-106 f.

The bottom surface of the pad 120 a includes a platform area 124 and araised spherical member 126 in the center of the platform area 124. Theplatform area 124 covers at least a portion of the entire area of thepad 120 a and does not cover the entire area under the top surface 122.While the spherical member 126 is illustrated in this shape in thisimplementation, other raised shapes may be used in other exemplaryimplementations.

The spherical member 126 engages a top surface 128 of an upper levelingplate 106 a and may exert forces on the top surface 128. The upperleveling plate 106 a, in cooperation with the other upper levelingplates and the lower leveling plates 104 a-104 f act to maintain the pad120 a and the other pads together in a parallel plane.

Referring also to FIGS. 9 and 10, a perspective view illustrates abottom surface of the cover 130 (FIG. 9) and a perspective viewillustrates a top surface 132 of the cover 130 (FIG. 10). The cover 130may be disc-shaped or spherical-shaped and may be configured to encloseother components of the medical device 100. The cover 130 works incooperation with the base ring 102 hold the assembly together.

As discussed above, the top surface 132 may function as a contactsurface of a vertebrae within a body of a patient. A bottom surface 972of the cover 130 provides a contact surface for a top of thecompressible member 134 to contact. The cover 130 defines acircumferential wall 974 having a lip 976 at the top of the wall 974.The lip 976 may bend or curve slightly inward towards the center of thecover 130 such that when assembled together with the other components ofthe medical device 100, the lip 976 may hold or at least assist inholding the assembled device together.

Referring also to FIGS. 11-13, different views of the assembled medicaldevice 100 are illustrated in cross-section. FIG. 11 illustrates a topview of the medical device 100. FIG. 12 illustrates a cross-section viewalong the line A-A of the view in FIG. 11. FIG. 13 illustrates across-section view along the line B-B of the view in FIG. 11.

FIGS. 12 and 13 illustrate the assembled medical device 100. Thecross-sections of the medical device 100 illustrate the base ring 102, alower leveling plate 104 a, an upper leveling plate 106 a, a pad 120 awith a raised spherical member 126 providing force on the upper levelingplate 106 a, a cover 130 and a compressible member 134. FIG. 12illustrates the member 118 a extending through the upper leveling plate106 a to maintain the position of the upper leveling plate 106 a withinthe base ring 102. FIG. 13 illustrates the member 112 a extendingthrough the lower leveling plate 104 a to maintain the position of thelower leveling plate within the base ring 102.

The lip 976 of the cover 130 extends beyond and overlaps with the basering 102 to hold the assembly together. The cover 130 and the base ring102 provide contacting surfaces to the vertebrae within the body of thepatient.

FIG. 14 is a flow chart illustrating an exemplary process 1400 includingthe use of the medical device 100. Process 1400 includes inserting aprosthetic disc into a portion of an anatomical structure within a bodyof a patient (1410). The prosthetic disc may, for example, be themedical device 100 of FIG. 1.

The prosthetic disc may include a base ring (e.g., the base ring 102),multiple layers of multiple leveling plates configured to equalizeforces applied to the contact surface of the base ring (e.g., lowerleveling plates 104 a-104 f and upper leveling plates 106 a-106 f) and alayer of multiple pads with each of the pads having a top surface and abottom surface (e.g., pads 120 a-120 f). The top surface of the pads maybe configured to maintain a parallel plane and the bottom surface ofeach of the multiple pads may be configured to engage a top surface ofone of the layers of the leveling plates. The prosthetic device mayinclude a cover configured to enclose the multiple layers of theleveling plates, the layer of the multiple pads and the base ring (e.g.,cover 130 of FIG. 1).

Process 1400 includes contacting an outer surface of the base ring to avertebra (1420) and contacting an outer surface of the cover to avertebra (1430). For example, the contact surface 108 of the base ring102 may contact a vertebra (1420) and the top surface 132 of the cover130 may contact a vertebra (1430).

The various components of the medical device 100 described herein can beformed with any biocompatible material used for such a medical device.For example, each of the various components can be formed with one ormore biocompatible plastics and/or one or more biocompatible metals suchas, for example, titanium and stainless steel.

While certain features of the described implementations have beenillustrated as described herein, many modifications, substitutions,changes and equivalents will now occur to those skilled in the art. Itis, therefore, to be understood that the appended claims are intended tocover all such modifications and changes as fall within the scope of theembodiments. It should be understood that they have been presented byway of example only, not limitation, and various changes in form anddetails may be made. Any portion of the apparatus and/or methodsdescribed herein may be combined in any combination, except mutuallyexclusive combinations. The embodiments described herein can includevarious combinations and/or sub-combinations of the functions,components and/or features of the different embodiments described.

What is claimed is:
 1. A method for inserting an implant into a portionof an anatomical structure within a body of a patient, said methodcomprising: inserting the implant in the intervertebral space, whereinthe implant comprises: a base ring configured to contact a firstvertebral body; at least one lower leveling plate, each lower levelingplate configured to engage an inner surface of the base ring; at leaston upper leveling plate, each upper leveling plate configured to engagea top surface of a corresponding lower leveling plate and held in placewithin the base ring; a cover configured to enclose the at least onelower leveling plate, the at least one upper leveling plate, and thebase ring, wherein the cover is configured to contact a surface of asecond vertebral body; and a compressible member arranged through acenter of the at least one lower leveling plate and the at least oneupper leveling plate, wherein the compressible member has a top surfaceconfigured to engage the cover, wherein the at least one lower levelingplate comprises a plurality of lower leveling plates disposed in amanner that is symmetrical about a center of the base ring.
 2. Themethod of claim 1 wherein the base ring defines a disc shape, the basering defining a space between an inner wall and an outer wall, the spacebetween the inner wall and the outer wall configured to receive the atleast one lower leveling plate and the at least one upper levelingplate.
 3. The method of claim 2 wherein the inner wall of the base ringdefines an area to receive the compressible member.
 4. The method ofclaim 1, wherein the implant further comprising at least one pad havinga top surface and a bottom surface, the top surface of each of the atleast one pad arranged and configured to maintain a parallel plane andthe bottom surface of each of the at least one pads engaging a topsurface of a corresponding upper leveling plate.
 5. The method of claim4 wherein the top surface of each of the pads is flat and the bottomsurface of each pads defines a platform having a raised spherical memberon a top surface of the platform.
 6. The method of claim 4, wherein eachof the pads maintains the parallel plane using the at least one lowerleveling plate and the at least one upper leveling plate.
 7. The methodof claim 1 wherein each of the at least one lower leveling plate andeach of the at least one upper leveling plate are configured to equalizeand distribute forces applied to a contact surface of the base ring withthe first vertebral body and a contact surface of the cover with thesecond vertebral body.
 8. The method of claim 1 wherein the coverdefines a circumferential wall having a lip at a top of thecircumferential wall.
 9. The method of claim 1 wherein the compressiblemember comprises a biocompatible, flexible material.
 10. A method forpositioning an intervertebral implant in a treated area of anintervertebral space between vertebral bodies of a spine, said methodcomprising: inserting the implant in the intervertebral space, whereinthe implant comprises: a base ring configured to be implanted within abody of a patient; a layer of lower leveling plates, wherein each lowerleveling plate has a non-planar bottom surface that engages an innersurface of the base ring; a layer of upper leveling plates, respectivelycorresponding to the layer of lower leveling plates, wherein each upperleveling plate contacts a top surface of a corresponding upper levelingplate; and a cover disposed in a manner to enclose the base ring, thelayer of lower leveling plates, and the layer of upper leveling plates;wherein a compressible member is disposed in the center of the medicaldevice and engages each of the base ring, the layer of leveling plates,the layer of upper leveling plates, and the cover.
 11. The method ofclaim 10 wherein the base ring defines a disc shape, the base ringdefining a space between an inner wall and an outer wall, the spacebetween the inner wall and the outer wall configured to receive thelayer of lower leveling plates and the layer of upper leveling plates.12. The method of claim 11 wherein the inner wall of the base ringdefines an area to receive the compressible member.
 13. The method ofclaim 10, further comprising a plurality of pads each having a topsurface and a bottom surface, the top surface of each of the pluralityof pads arranged and configured to maintain a parallel plane and thebottom surface of each of the plurality of pads engaging a top surfaceof a corresponding upper leveling plate.
 14. The method of claim 13wherein the top surface of each of the plurality pads is flat and thebottom surface of each of the plurality of pads defines a platformhaving a raised spherical member on a top surface of the platform. 15.The method of claim 13 wherein each of the plurality of pads maintainsthe parallel plane using the layer of lower leveling plates and thelayer of the upper leveling plates.
 16. The method of claim 10 whereinthe layer of lower leveling plates and the layer of upper levelingplates are configured to equalize and distribute forces applied to thebase ring and the cover from adjacent vertebral bodies.
 17. The methodof claim 10, the layer of lower leveling plates is disposed in a mannerthat is symmetrical about a center of the base ring.
 18. The method ofclaim 10 wherein the cover defines a circumferential wall having a lipat a top of the circumferential wall.
 19. The method of claim 10 whereinthe compressible member comprises a biocompatible, flexible material.